Search for ultra high energy neutrinos using the surface detector of the Pierre Auger observatory

El Detector de Superficie del Observatorio Pierre Auger es sensible a neutrinos de todos los sabores con energía por encima de 0,1 eV. Estos interactúan en la atmósfera mediante corrientes cargadas y neutras, iniciando cascadas atmosféricas extendidas. Al interactuar profundo en la atmófera a incidencia casi horizontal, los neutrinos pueden ser distinguidos del fondo producido por rayos cósmicos de origen hadrónico gracias a la estructura temporalmente extendida de las señales que producen en los detectores Che- renkov de agua. En este trabajo se presenta por primera vez un análisis basado en neutrinos descendentes. Se describe el procedimiento de búqueda, las posibles fuentes de fondo, el método desarrollado para calcular la exposición y las incertezas sistemáticas asociadas. Ningún candidato a neutrino fue encontrado en los datos adquiridos entre 1-Ene-2004 hasta 31-May-2010. Asumiendo un flujo diferencial típico Φ(Eν ) = k · EνE-2 , se fijo un límite sobre el flujo de neutrinos de cada sabor de k <1.65 × 10E−7 GeV cmE−2 sE−1 srE−1 con un nivel de confianza del 90 %.The Surface Detector of the Pierre Auger Observatory is sensitive to neutrinos of all flavours above 0.1 EeV. These interact through charged and neutral currents in the atmosphere giving rise to extended air showers. When interacting deeply in the atmosphere at nearly horizontal incidence, neutrinos can be distinguished from regular hadronic cosmic rays by the broad time structure of the signals in the water-Cherenkov detectors. In this paper we present for the first time an analysis based on down-going neutri- nos. We describe the search procedure, the possible sources of background, the method to compute the exposure and the associated systematic uncer- tainties. No candidate neutrinos have been found in the data collected from 1 January 2004 to 31 May 2010. Assuming a differential flux Φ(Eν ) = k · EνE-2 in the energy range from 0.1 to 10 EeV, we place a 90 % CL upper limit on the single flavour neutrino flux of k < 1.65 × 10E−7 GeV cmE−2 sE−1 srE−1Fil: Tiffenberg, Javier Sebastián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

Dual-sided Charge-Coupled Devices

Existing Charge-Coupled Devices (CCDs) operate by detecting either the electrons or holes created in an ionization event. We propose a new type of imager, the Dual-Sided CCD, which collects and measures both charge carriers on opposite sides of the device via a novel dual-buried channel architecture. We show that this dual detection strategy provides exceptional dark-count rejection and enhanced timing capabilities. These advancements have wide-ranging implications for dark-matter searches, near-IR/optical spectroscopy, and time-domain X-ray astrophysics.Comment: 12 pages, 12 figures. v2: matches published version. Merged appendices into the main text, added dark matter projected reach plo

Charge-Collection Efficiency in Back-Illuminated Charge-Coupled Devices

Low-noise fully depleted charge-coupled devices have been identified as a unique tool for dark-matter searches, low-energy neutrino physics, and x-ray detection. The charge-collection efficiency (CCE) for these detectors is a critical performance parameter for current and future experiments. We present a technique to characterize the CCE in back-illuminated CCDs based on soft x rays. This technique is used to study two different detector designs. The results demonstrate the importance of the backside processing for the detection of charge packages near threshold, showing that a recombination layer of a few microns significantly distorts the low-energy spectrum. The studies demonstrate that the region of partial charge collection can be reduced to a thickness of less than 1μm with adequate backside processing.Fil: Fernández Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados UnidosFil: Andersson, Kevin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Botti, Ana Martina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Rodrigues Ferreira Maltez, Dario Pablo. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Studying single-electron traps in newly fabricated Skipper-CCDs for the Oscura experiment using the pocket-pumping technique

Understanding and characterizing very low-energy ( ∼ eV) background sources is a must in rare-event searches. Oscura, an experiment aiming to probe electron recoils from sub-GeV dark matter using a 10 kg skipper-CCD detector, has recently fabricated its first two batches of sensors. In this work, we present the characterization of defects/contaminants identified in the buried-channel region of these newly fabricated skipper-CCDs. These defects/contaminants produce deferred charge from trap emission in the images next to particle tracks, which can be spatially resolved due to the sub-electron resolution achieved with these sensors. Using the trap-pumping technique, we measured the energy and cross section associated with these traps in three Oscura prototype sensors from different fabrication batches which underwent different gettering methods during fabrication. Results suggest that the type of defects/contaminants is more closely linked to the fabrication batch rather than to the gettering method used. The exposure-dependent single-electron rate (SER) of one of these sensors was measured ∼ 100 m underground, yielding ( 1.8 ± 0.3 ) × 10 − 3 e − /pix/day at 131 K. The impact of the identified traps on the measured exposure-dependent SER is evaluated via a Monte Carlo simulation. Results suggest that the exposure-dependent SER of Oscura prototype sensors would be lower in lower background environments as expected

Smart Readout of Nondestructive Image Sensors with Single Photon-Electron Sensitivity

Image sensors with nondestructive charge readout provide single-photon or single-electron sensitivity, but at the cost of long readout times. We present a smart readout technique to allow the use of these sensors in visible light and other applications that require faster readout times. The method optimizes the readout noise and time by changing the number of times pixels are read out either statically, by defining an arbitrary number of regions of interest in the array, or dynamically, depending on the charge or energy of interest in the pixel. This technique is tested in a Skipper CCD showing that it is possible to obtain deep subelectron noise, and therefore, high resolution of quantized charge, while dynamically changing the readout noise of the sensor. These faster, low noise readout techniques show that the skipper CCD is a competitive technology even where other technologies such as electron multiplier charge coupled devices, silicon photo multipliers, etc. are currently used. This technique could allow skipper CCDs to benefit new astronomical instruments, quantum imaging, exoplanet search and study, and quantum metrology.Fil: Chierchie, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Fernández Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Stefanazzi, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, Gustavo Indalecio. Fermi National Accelerator Laboratory; Estados UnidosFil: Uemura, Sho. Universitat Tel Aviv; Israe